Unless otherwise indicated herein, the description in this section is not prior art to the claims in this application and is not admitted to be prior art by inclusion in this section.
The present disclosure relates to an image forming apparatus capable of executing a high-speed duplex-printing mode, and a non-transitory computer-readable recording medium having an image formation program recorded thereon.
Some image forming apparatuses, such as digital multifunction peripherals, are configured to execute a high-speed duplex-printing mode in which duplex image formation is performed in parallel while a plurality of sheets are being simultaneously circulated. The high-speed duplex-printing mode enables duplex printing on a plurality of sheets with higher speed as compared to duplex printing on each sheet in turn.
To ensure high-speed performance, it is preferable to at least sequentially print on one side (the side printed first, hereinafter referred to as the “first side”) of a plurality of sheets, starting from the leading sheet in a circular direction in accordance with the number of sheets capable of being simultaneously circulated.
For example, in an apparatus in which four sheets are capable of being circulated (four-sheet circulation), if six pages are to be printed in duplex mode, the first sides of three consecutive pages P2, P4, and P6 are printed in order, starting from the leading sheet. After that, the second sides P1, P3, and P5 are printed in order starting from the leading sheet.
The high-speed duplex-printing mode is executed in such a manner that duplex-printing requests for individual sheets are issued through a print job process, and a video controller issues, based on the duplex-printing requests, simplex-printing requests for individual sides at appropriate timings. After the simplex-printing requests have been issued, image formation is performed on the sheets through an output process performed by an engine controller.
Typically, simplex-printing requests are issued using, as triggers, (i) a request to the video controller for duplex printing for each sheet and (ii) completion of an output process performed by the engine controller in response to a simplex-printing request. Using both the triggers enables issuance of simplex-printing requests at appropriate timings. However, the timing at which a duplex-printing request for each sheet is issued may be delayed depending on how a print job is processed, and therefore issuance of a simplex-printing request (itself triggered by issuance of the duplex-printing request) is not performed at an appropriate timing in some cases. If the duplex-printing request for the second or subsequent sheet is delayed, duplex printing may be performed in a normal duplex-printing mode or a defective high-speed duplex-printing mode.
For example, if a duplex-printing request for the second sheet is delayed, after an output process for a simplex-printing request for the first side of the first sheet is completed but before the duplex-printing request is input, a simplex-printing request for the second side of the first sheet is issued as a trigger upon completion of the output process for the first side of the first sheet (normal duplex-printing mode). Also, if a duplex-printing request for the third sheet is delayed, after an output process for a simplex-printing request for the first side of the first sheet is completed but before the duplex-printing request is input, a simplex-printing request for the second side of the first sheet is issued as a trigger upon completion of the output process for the first side of the first sheet (defective high-speed duplex-printing mode).